In U.S. Pat. No. 6,474,118 entitled SCISSORS LATCH LOCK issued Nov. 5, 2002 to Richard A. Martinez, the disclosure of which is incorporated herein by reference, a lockable latch and strike are disclosed that can be mounted on members, structures or devices that are to be moved toward each other to close or closed positions that are to be secured by locked engagement of the latch with the strike. Toward this end, the latch has a generally rectangular housing from which extends a single post-like projection having a tapered outer end that facilitates insertion of the post-like projection into a single opening defined by the strike.
The latch of the aforementioned Martinez patent also has a pair of latch bolts, inner end regions of which extend into and are pivotally connected to the housing. Outer end regions of the latch bolts are movable between unlatched and latched positions. When in the unlatched positions, the latch bolts reside closely alongside the single post-like projection of the latch in a tight, compact array that facilitates inserting the outer end region of the post-like projection and the outer end regions of the latch bolts into the single opening of the strike. When in the latched positions, the outer end regions of the latch bolts project away from each other and from opposite sides of the single post-like projection to enable the bolt-carried tooth formations to engage latching formations that are defined by the strike at locations near opposite end regions of the single opening of the strike.
When the latch of the Martinez patent is to engage its strike, the outer end region of the post-like projection and the outer end regions of the latch bolts are inserted in a tightly grouped array into the opening of the strike, whereafter the outer end regions of the latch bolts are moved away from each other and away from opposite sides of the post-like projection of the latch to engage the latching formations of the strike. When the outer ends of the latch bolts and the post-like projection are in a tightly grouped array that permits their being inserted into and withdrawn from the strike's opening, the latch bolts are said to be in their unlatched positions. When the outer end regions of the latch bolts are moved away from each other and away from opposite sides of the outer end region of the post-like projection to bring the tooth formations into latching engagement with the latching formations of the strike, the latch bolts are said to be in their latched positions.
If the outer end region of either of the latch bolts latchingly engages its associated strike-defined latching formation, the latch is, in fact, latched into engagement with the strike because even one such latching engagement prevents the latch from being moved out of engagement with the strike. Thus, only when neither of the latch bolts latchingly engages its associated strike-defined latching formation is the latch actually unlatched from the strike because only then can the latch be separated from the strike by withdrawing the latch bolts and the post-like projection from the single opening of the strike.
Although the latch bolts of the lockable latch disclosed in the Martinez patent do not rely on housing-carried springs to establish or to maintain their latched engagement with the strike, the latch does rely on a pair of housing-carried springs to disestablish latched engagement of the latch with the strike by moving the outer end regions of both of the bolts from their extended latched positions to their retracted unlatched positions so the post-like projection and the latch bolts can be withdrawn from the opening of the strike.
Each of the housing-carried springs of the latch disclosed in the Martinez patent is relatively small and relatively weak. Each of these springs biases only an associated one of the two latch bolts toward its unlatched position. Neither of these springs serves to “backup” the action of the other. If one should fail to perform its intended function, the other is not designed to attempt to perform the function of the spring that failed. Thus, if one or both of these relatively small, relatively weak housing-carried springs should fail (for example, as the result of fatigue, breakage or simply due to its insufficiently small biasing force) to retract one or both of the latch bolts at a time when an owner operator has used a correctly configured key to turn a key-operated plug of the latch from the locked position to the unlocked position, the latch will remain in latched engagement with the strike—which is to say that the latch will not respond, as intended, to the unlocking efforts of the owner operator to release its engagement with the strike.
Because the tooth formations on the outer end regions of the latch bolts of latches of the type disclosed in the Martinez patent often tightly engage the latching formations of their associated strikes, the relatively weak housing-carried springs of these latches sometimes fail to dislodge, release and move the tooth formations from latchingly engaging the associated strikes. Thus, it is known for one or both of the latch bolts to remain stuck in latched engagement with the strike, which prevents withdrawal of the post-like projection and the associated latch bolts from the strike opening.
In other words, the latch does not release: it does not unlatch despite repeated turnings of the key-operated plug of the latch from the locked to the unlocked position. And, when repeated turnings of the key-operated plug of one of these latches (from locked to unlocked positions) brings no corresponding unlatching movement of one or both of the associated latch bolts, the owner operator may become frustrated, and may be inclined to pound or pry on the latch and/or the strike in an effort to dislodge the stuck latch bolts so they will move properly to their unlatched positions under the influence of their housing-carried springs.
Because latch damage may occur if latches or their associated strikes are pounded or pried on during efforts to dislodge and jar loose one or both of the toothed latch bolts from latched engagement with the associated strike, a need exists for an improved form of latch that includes a mechanism designed to effect positive movement of the associated latch bolts from latched to unlatched positions when the associated key-operated plug is turned from locked to unlocked positions. What is needed is a latch that does not depend on the action of springs to move its latch bolts from latched to unlatched positions, and therefore will not need to be pounded on or pried to jar one or both of its latch bolts out of latched engagement with the associated strike when the key-operated plug of the latch is turned from a locked to an unlocked position.
Yet another shortfall of latches and strikes of the type disclosed in the Martinez patent stems from their reliance on insertion of a single post-like projection of the latch into a single opening of the associated strike to effect proper alignment (of the movable members, structures or devices on which the latches and strikes are mounted) when the latches are to be moved into latching engagement with their associated strikes. Relying on the tapered outer end region of only one post-like projection being inserted into only one strike-defined opening to align members, structures or devices that carry a latch and strike for movement toward close or closed positions that are to be maintained by locked engagement of the latch and strike can prove frustrating and awkward, and can lead to bending or breakage of the single post-like projection and/or the outer end regions of the associated latch bolts, especially if the latch bolts should move away from opposite sides of the post-like projection (where the tooth formations of the latch bolts are intended to be shielded from contact by the post-like projection) thereby exposing one or more of the tooth formations to unwanted contact at the same time that efforts are under way to align and insert the post-like projection into the opening of the associated strike.
An improved latch is desired that provides a stronger and more reliable device than is afforded by a single post-like projection which is intended to be aligned with and inserted into a single strike-defined opening as disclosed in the Martinez patent for aligning latch- and strike-carrying members during their movement toward close or closed positions that are to be maintained by latched engagements of the associated latch bolts with their associated strikes.